Heat exchanger



Dec. 9, 1947. k 3. A, WORN TAL 2,432,362

HEAT ExcHANGEn Filed Aug. l, 1942 @zal .30 27 4 .56 'eorye. am and enormous pressure.

UNITED STATES PATENT OFFICE HEAT EXCHANGER George A. Worn, Greenwich, Conn., and Edward A. Bertram, Mount Vernon, N. Y., assignors to The Lummus fompany, New York, N. Y., a corporation of Delaware Application August 1, 1942, Serial No. 453,234

6 Claims. l This invention relates to improvements in heat exchangers.

In connection with many chemical processes requiring heat for a reaction, it is common to employ heat exchangers to heat a strea-m of materials passing toA a reaction chamber by heat exchange with a hot stream of reaction products discharged from the reaction chamber.

In some processes, such as certain hydrocarbon conversion processes, for example, great heat desired reaction. For example, in the chlorobenzene process for the manufacture of phenol,

the conversion of chlorobenzene to phenol is carried out under a temperature exceeding 700 F. and a pressure exceeding 4,000 pounds per square inch. Since the heat exchanger is in communication with the reaction chamber or reaction coils, it is subjected to the strain of said The usual type of heat exchanger is not capable of withstanding the strain of such conditions.

An important object of the present invention is to provide, for the aforesaid high pressure service, a relatively small unit heat exchanger designed throughout for adequate strength and and pressure are required in order to obtain a durability, high heat transfer efficiency and low cost of manufacture.

Another object of the inventionis to provide a multi-unit high-pressure heat exchange appa-- ratus, in which the units and their interconnections aredesigned to render the apparatus leakproof throughout and, at the same time, enable ready disconnection, take-down and servicing of the units.

Other objectsof the invention will appear hereinafter. i

In the drawing:

Fig. 1 is a horizontal sectional View approximately on theA line I--I of Fig. 5 and with parts broken away;

Fig. 2 is a vertical longitudinal sectional view of one o f the improved heat yexchanger' units, approximately on the line 2--2 of Fig. 5 and upon an enlarged scale;

Fig. 3 is an enlarged vertical cross section on the line 3-3 of Fig. 2;

Fig. i is a perspective view of one of the im-l proved tube units partly broken away; and

Fig. 5 is an end elevation of a plurality of the heat exchange units connected in series.

In accordance with a preferred form of embodiment of our invention, we have shown ,in Figs. 1 and 5 three of the improved heat exchanger units designated IU, II and I2 in a horizontal row and' connected in series. It will be understood that such units may be so connected in any required number and that they may be arranged in superimposed banks if desired.

Each unit comprises` an outer pipe or tube closed at one end, a cover detachably secured to the'opposite end of said tube, and an inner tube unit connected to said cover. The outer tubes of the diiierent units are, in the present instance connected in series for shell-side circulation of one uid. and the inner tubing of the different units is connected in series for tube-side circhlation of anotherfluid.

The outer tube of each unit is a welded Icon- 'struction formed for convenience in three sec` tions. There is a longmain tube section l3 which forms most of the length of the tube.. A cover I4 is welded as `at I5 to one end o f s aid main section `and forms a permanent closure therefor. An annular flange section I6 is welded as at I'I to the opposite end of section I3 andfis formed with a thick peripheral iiange I8, the tubular neck of which tapers so that itsr thickness decreases to the tube section I3. The bore of the head section is ared at its outer end as at I9, and the section `is formed With a relieved face around the mouth of the bore and with a gasket-receiving groove 28 in said face. A thick cover plate or disk 2| has a similar face and a similar groove 22 in opposition to the face and groove respectively of the head section. A metal gasket ring 23 of a depth exceeding the com bined depth of said grooves has its edges seated in the grooves. 'I'he grooves have ilat bottoms and inwardly converging side Walls, and the edges of the gasket are beveled in the grooves. Bolts 24 extend through holes in the flange I8 and the cover plate 2l and have nuts 25 screwed upon 4their opposite ends to secure the plate and hold the gasket under compression.

Cover plate 2| has a i'luid inlet passage 26 and a fluid outlet passage 21 extending between sages may be readily formed by boring inwardly part way thrQuESh the cover plate and then borto meet the rst bores.

of the plate at an angle y At the outer face of the plate the passages are counterbored to provide them with a flare or bevel seat 30.

Within the outer tube of each heatexchanger unitvthere is an inner tube unit forming a small tube bundle dened by a single bifurcated U-tube. Tubular stems 3| and 32, at the forward end of theouter tuba-form the end portions of said U- tube. Stem 3| is the inlet stem and Opens into a 'tubular fork 33. From said fork, parallel ing from the inner face 'branch tubing 34 extends forwardly for the major portion of the length of the outer tube, forms retrn bends -35 and from said bends extends in a reverse direction to a tubular fork 36 opposite the rst fork and connected to the outlet stem 432. In the present instance there are two of the' branch tubes in each leg of the U-tube and they provide for divided flow from the stem 3| to the stem 32. In cross section the tubes are in a rectangular arrangement, as shown in Fig. 3. Their caliber is smaller than that of the stems. At their outer ends the stems 3| and 32 are secured in sealed communication with the passages 26 and 21-`in the cover plate. The outer end portions of the stems diverge in order toreach the passages, and the ends of the stems contact squarely with the 'abutments 28 and are permanently secured to the cover plate at 28a by welding material in the counterbores 29. The tubes are thus integrated with the plate 2|. For supporting the tubing centered within the bore of the outer tube the lower tube portions have supporting lugs 31 welded to .them at points spaced therealong. Spacer blocks 38 disposed between and welded to the branch tubes at points spaced along the lata clamping ring 49 surrounds the tube.

. 4 central bore receiving the unenlarged portion of the tube, and bores receiving the stud bolts 45. The outer ends of the latter bores are ared to receive conical washers 41, and nuts are screwed on the bolts against said washers. Between the inner side of the yoke and the enlarged tube end, When the nuts are tightened, said ring is f orcedby the yoke against the rear shoulder of the enlarged tube end to., force and hold the latter sealed against its seat. i

Transverse piping connects the outer tubes of the exchanger units for ilow of the fluid to be cooled through the units win series. The main tube section I3 of the unit l2 has welded thereto, ad-

` jacent one of its ends, av nipple 5U which comvmunicates with anl opening in said tube section and forms the inlet to the tube. 'Near its opposite end said tube section has an outlet opening communicating with a nipple 5| welded to the tube section and also welded as at 52 to a nipple 53. The latter is welded to the main tube section of unit and opens through an inlet port near one end of that section. Near its opposite end said main tube section of unit is in communi cation with an adjacent end portion of the main tube section of unit I0 through nipples 54 and 55 welded similarly to the nipples 5| and 53. A nipple 56 welded to the said tube section of umt ||l, near the opposite end of the latter, forms an outlet for unit l0. The said nipples, individual to the respective units, may be welded in at the place of manufacture of the unit, and the apter serve to hold said tubes in a transversely A spaced relation.

The inner tube unit may be satisfactorily constructed in the following manner: Two pairs of tubes of a length suitable for forming the branch tubing are selected and adjacent end portions of `the tubing in said pairs are forged together to form the return bends between the pairs. The opposite end portions of the tubes in one pair are forged together to form the vreturn bend or fork 33 and also form a nipple 33a. The opposite ends of the other pair of tubes are forged together `to .form the return bend or fork 36 and also form a nipple 36a. The said nipples are welded, as at 39, to short tube sections which form therewith the stems 3| and 32.

of unit a U-tube 42 leading from the outlet passage of unit to the inlet passage of unit l2, and a discharge pipe 43 leading from the outlet passage of unit |2.

Each of the said externaI tubes has a sealed connection with its respective communicating passage in the cover plate 2|. For that purpose, each tube end communicating with a passage ln one of the cover plates has an enlarged end 44 formed by upsetting the metal of the tube. Said enlarged end is seated in the are 30 of the communicating passage and is preferably groundv lor line contact around the inside of the nare. There is a clamping device to maintain a compression seal of each of said tube ends. Each cover plate bears a. pair of stud bolts 45 at opposite sides of propriate nipples of the different units may be welded together at the place of erection of the apparatus.

Provision is made for protecting the inner tubing of each unit from erosion by the fluid entering the outer tube. For that purpose impingement shield plates 51 are welded to one side of the branch tubing 35 in a position to face the inlet port of the outer tube. The entire unit may also be provided with cradles 58 or similar devices to support the unit. y

A highly efficient heat exchange unit is provided .by this internal tube construction. It is possible by using the bifurcated tubes to obtain the largest amount of tube surface'for the outer tube sizeand to still provide easy detachability of 4: the entire unit. Leakage is prevented by integrat.

ing the tubes with the cover plates, it being understood that welding is preferred but that rolling or other sealing can be used. The external connections are also most effectively made by the particular means shown although it is possi-'- ble to weld the external connections or to make other forms of joints if desired. The assembly issimple, easily and cheaply built and of particular radvantage with high pressure requirements.

While we have disclosed a preferred form of embodiment of our invention, it will be understood that it is possible to modify details of the structure disclosed without departing from the invention as defined in the appended claims.

We claim:

1. In aheat exchanger comprising an outer tube having a fluidinlet and a uid outlet and a closure for said tube detachably secured over one end thereof and having a fluid inlet passage and a fluid outlet passage, a bifurcated inner U-tube within said outer tube and comprising inlet and outlet stems forming the end portions of the U-tube and a plurality of tube branches leading from the inlet stem longitudinally within the outer tube and forming return bends and thence leading back to the outlet stem for divided' flow from the inlet stem to the outlet stem, said inlet and outlet stems `being welded to said closure in sealed connection with said inlet and' outlet passages respectively, projections borne by said inner tube to engage the interior of the outer tube and `hold the inner tubing centered therein, spacing means secured to the branches of the inner tube to hold the branches in a i spaced relation to each other, and impingement shield means borne by the inner tube and facing the said inlet of the outer tube.

2. In a heat exchanger of the 'double-tube' angles to the plane of the stems, for evenly distributed forward and,Y return passage of fluid from the inlet stem to the outlet stem, the forward and return reaches of said tube branches being, in cross section, all spaced in succession around a central spacel to form a tube bundle extending longitudinally within the outer tube and fully confined therein and of polygonal cross section, said bundle being supported centrally of the outer tube and being relatively closely surrounded by the latter and said stems, branchesand return bendsbeing continuous and integral and forming, together with said closure, a permanent unitary structure.

4. A heat exchanger of the double-tube type and including an outer tube adapted for passing a fluid longitudinally therethrough, a detachable closure for one end of said tube and having an stern arranged alongside of each other in apf proximately the same plane and forming the end portions of the U-tube and both inpermanent sealed connection with said closure at said inlet passage and said outlet passage respectively whereby said inner tube may be withdrawn from said outer tube upon disassembly of said exchanger, and a pair of tube branches, of approximately equal length and equal diameter leading forwardly from the inlet` stem said branches being located in a plane at right angles to the plane of the stems and forming return bends in planes substantially parallel to said plane of the stems and thence leading rearwardly to the outlet stem and opening thereinto, such rearwardly leading branches being located in a plane at right angles to the plane of the stems, for evenly distributed forwardl and return passage of iluid from the inlet stem to the outlet stem, the forward and return reaches of said tube branches being, in cross section, all spaced in succession around a central space to form a tube bundle extending longitudinally within the outer tube and fully confined therein and of polygonal crosssection, said bundle being supported centrally of the outer tube and being relatively closely surrounded by the'latter and .said stems, branches and return bends being continuous and integral and forming, together with vsaid closure, a permanent unitary structure.

3. In a heat exchanger of the double-tube type, comprising an outer tube adapted for passing a iluid longitudinally therethrough and a detachable closure for one end of said tube and having an inlet passage and an outlet passage; an elongated U.shap ed inner' tube within said outer tube and comprising an inlet stem and an outlet stem arranged alongside of each other in approximately the same plane and forming the end portions of the U-tube and both in permanent sealed connection with said closure at said inlet passage and said outlet passage respectively whereby said inner tube may be withdrawn from said outer tube upon disassembly7 of said exchanger, aV pair of superimposed tubebranches, of approximately equal length and equal diameter leading forwardly from the inlet stem said branches being located in a common plane which is at right angles to the plane of the stems and forming superimposed return bends in planes substantially parallel to said plane of the stems and thence leading rearwardly to the outlet stem and openingA thereinto,` such rearwardly leading branches being arranged in superimposed relationship and being located in a plane at right inlet passage and an outlet passage, an elongated U-shaped inner tube within said outer tube and comprising an inlet stem and an outlet stern arranged alongside of each other in approximately the same plane and forming the end portions of the U-tube and both in permanent sealed connection with said closure at said inlet passage and said outlet passage respectively whereby said inner tube maybe withdrawn from said outerV tube upon disassembly of said exchanger. a pair of parallel tube branches leading forwardly from the inlet stem and forming return bends in planes substantially parallel to each other and to said plane of the stems and thence leading rearwardly in parallel relationship, and opening into the outlet stem, for forwardand return passage of fluid from the inlet stem to the outlet stem, the forward and return reaches of said'tube branches being, in crossl section, all spaced around a central space to form a tube bundle extending longitudinally within the outer tube and fully Aenclosed therein and of polygonal cross section, said bundle being supported centrally of the outer tube and being relatively closely surrounded bythe latter and said stems, branches, and return bends being continuous and integral and forming, together with said closure, a permanent unitary structure.

5. In a heat exchanger including an outer tube with means for passing a fluid longitudinally therethrough, and inner tubing longitudinally arranged within the outer tube and comprising a plurality of sections of U-form with a common fluid inlet stem and a common fluid outlet stem bothf/at one end of the tubing; a closure plate for 4the outer tube detachably secured and sealed to one end of the outer tube and having therethrough an inlet passage and an outlet passage both extending from the outer face of the closure plate to the inner face thereof and in sealed connection with said stems respectively whereby said inner tube may be withdrawn from said outer tube upon disassembly of said exchanger. said passages being flared outwardly at the outer face of the plate, a pair of outer pipes each having an enlarged end integral therewith, said pipe ends fitting in the flares of said plate passages respectively, clamping jmembers for said pipe endsrespectively, each of said clamping members having an opening receiving the unenlarged portion of its respective pipe and being formed to engage the shoulder formed by the enlarged end of the pipe, and screw means associated with` each clamping member and connected to said closure plate at opposite sides of each of said passages to eiect operation of either Vof SaidbIamping members for clamping or release of either of said pipe 7 ends in the respective passage flare independently of the other pipe end.

6. In a heat exchanger comprising an outer l inlet and outlet stems forming the end portions of the U-tube and a plurality of tube branches leading from the inlet stem longitudinally within the outer tube and forming return bends and thence leading back to the outlet stem for divided flow from the inlet stem to the outlet stem, said inlet and outlet stems being secured to said closure in sealed connection with said inlet and outlet passages respectively, projections borne by said inner tube to engage the interior of the outer tube and hold the inner tubing centered therein, spacing means secured to the branches of the inner tube to hold the branches in a spaced relation to each other, and impingement shield means borne by the inner tube and facing ythe said inlet of the outer tube.

GEORGE A. WORN.

EDWARD A. BERTRAM.`

REFERENCES CITED The following references are of record in the le of this patent:l

UNITED STATES PATENTS Great Britain Nov. 1, 1934 

